1. Field of the Invention
The present invention relates to a technical field of semiconductor devices and methods for making the same. In particular, the present invention relates to a technical field of a method for making a semiconductor device including forming a single-crystal semiconductor thin film for constituting switching elements such as thin film transistors (hereinafter referred to as TFTs) on an insulating substrate, a semiconductor device produced by this method, a method for making an electro-optical device using the semiconductor device, an electro-optical device produced by this method, and an electronic apparatus using the electro-optical device.
2. Description of Related Art
Semiconductor technologies for forming a single-crystal silicon thin film on an insulating substrate and for forming semiconductor devices using the single-crystal silicon thin film are called silicon-on-insulator (SOI) technologies and have been widely studied because of their advantages, such as high-speed response, low electrical power consumption, and high integration density of pixels.
One of the SOI technologies is an SOI substrate production technology by adhesion of a single-crystal silicon substrate. This method, generally called an "adhesion process", includes adhering a single-crystal silicon substrate to a supporting substrate (an insulating substrate) by a hydrogen bonding force, reinforcing the adhering strength by heat treatment, and then thinning the single-crystal silicon substrate by grinding , polishing, or etching to form a single-crystal silicon layer on the supporting substrate. This process can directly thin the single-crystal silicon substrate and enables production of high-performance devices with silicon thin films having high crystallinity.
Applied methods of this adhering process have also been known, for example, a method including implantation of hydrogen ions into a single-crystal silicon substrate, adhering this substrate to a supporting substrate, and then separating a thin film silicon layer from a hydrogen-implanted region of the single-crystal silicon substrate by heat treatment (U.S. Pat. No. 5,374,564), and a method for forming an epitaxial single-crystal silicon thin film on a supporting substrate which includes epitaxial growth of a single-crystal silicon layer on the silicon substrate with a porous surface, adhering this substrate to a supporting substrate, removing the silicon substrate, and then etching the porous silicon layer (Japanese Patent Laid-Open Application No. 4-346418).
SOI substrates formed by the adhesion methods have been used in production of various devices, as well as general bulk semiconductor substrates (semiconductor integrated circuits), and have an advantage in which various materials can be used as a supporting substrate different from an advantage of the conventional bulk substrate. Transparent quartz and glass substrates, in addition to general silicon substrates, can be used as supporting substrates. As a result, for example, formation of a single-crystal silicon thin film on a transparent substrate enables formation of high-performance transistor elements using single-crystal silicon having high crystallinity in devices requiring light transmissivity, such as electro-optical devices such as a transmissive liquid crystal display device.